Sunday, May 15, 2011

Rainforest biome

Tropical Rainforest Biome

Tropical rainforest biome is the most complex and species-rich biome on the Earth. 80% of all world's biodiversity are found here.The reason for such amazing number of species is the ideal climatic conditions for plant growth: the warmth, and, more than anything - the moisture.This is compensated by extra high productivity - things decompose about 10 times quicker in tropical rainforests than in other biomes.The tropical rain forest is a forest of tall trees in a region of year-round warmth. An average of 50 to 260 inches (125 to 660 cm.) of rain falls yearly.

Rain forests belong to the tropical wet climate group. The temperature in a rain forest rarely gets higher than 93 °F (34 °C) or drops below 68 °F (20 °C); average humidity is between 77 and 88%; rainfall is often more than 100 inches a year. There is usually a brief season of less rain. In monsoonal areas, there is a real dry season. Almost all rain forests lie near the equator. This is compensated by extra high productivity - things decompose about 10 times quicker in tropical rainforests than in other biomes.

Rainforests now cover less than 6% of Earth's land surface. Scientists estimate that more than half of all the world's plant and animal species live in tropical rain forests. Tropical rainforests produce 40% of Earth's oxygen.

About 1/4 of all the medicines we use come from rainforest plants. Curare comes from a tropical vine, and is used as an anesthetic and to relax muscles during surgery. Quinine, from the cinchona tree, is used to treat malaria. A person with lymphocytic leukemia has a 99% chance that the disease will go into remission because of the rosy periwinkle. More than 1,400 varieties of tropical plants are thought to be potential cures for cancer.

All tropical rain forests resemble one another in some ways. Many of the trees have straight trunks that don't branch out for 100 feet or more. There is no sense in growing branches below the canopy where there is little light. The majority of the trees have smooth, thin bark because there is no need to protect the them from water loss and freezing temperatures. It also makes it difficult for epiphytes and plant parasites to get a hold on the trunks. The bark of different species is so similar that it is difficult to identify a tree by its bark. Many trees can only be identified by their flowers.

The canopy layer typically blocks the sunlight, creating the dark forest floor where the vegetation is scarce enough that we can walk on the forest floor.If a tree falls and opens the canopy, a myriad of small pant species start growing on the forest floor.If large parts of the canopy are opened after say, a hurricane, the vegetation on the forest floor becomes so dense that we would not be able to walk there - it becomes a real jungle.

Animals

Species such as lemurs and chameleons; and countless others such as Nile crocodiles, mongooses, tenrecs, and many species of bats, centipedes, frogs and lizards. Animals include Asian rhinos and Asian elephants, snow leopards and clouded leopards, crocodiles, bats, sun bears, black bears, bantengs, tarsiers and cobra snakes.A few species of marsupials such as wallabies and cuscus, but is more known for its bird-life with the famous birds of paradise, Victoria crowned pigeons and two species of cassowaries.

Plants

Rainforest plants thrive extremely well in their environment, because every plant loves a lot of water, and rainforests are indeed very wet places.This means rainforests are thick and dense, full of plant life, and packed with different plants - it gets so crowded that the biggest competition is this of sunlight. Every plant tries therefore to reach high up to not to miss out on sunligh.Large trees grow tall and spread out their canopies and block the light from reaching the ground. Some extra tall trees, called emergents, grow through that canopy, even higher. Others, like vines climb on tree trunks to reach the sunlight high up.

Orchids and epiphytes start growing high up in the trees when a bird drops a seed there. Shorter trees and other plants grow on the rainforest floor, where some light happens to reach the forest ground.When a high tree falls and opens up the canopy, smaller plants get a chance to start growing in the sunlight on the rainforest floor. Rainforest flora vary considerably between tropical and temperate rainforests; and between the rainforests on different continents. Tropical rainforest species are more numerous, while temperate rainforests have less layers and are more known for giant trees, mosses and epiphytes.

Temperate Rainforests Biome

This is a small biome in terms of area covered. Temperate rainforests are found along coasts in temperate regions. The largest temperate rainforests are on the pacific coast in North America, stretching from Alaska to Oregon. Other temperate rainforests are found along the coast of Chile, the United Kingdom, Norway, Japan, New Zealand, and S. Australia. The largest temperate rainforests are on the pacific coast in North America, stretching from Alaska to Oregon. Tropical rainforests are generally found between 30°N and 30°S latitudes, covering 6-7% of the Earth’s land surface.A temperate rainforest grows in four main layers, with different trees, flowers, and other plants in each layer.

The trees that make up the temperate rainforest are huge, and their value as timber is proportionate to their size. With forests elsewhere already cut, there is tremendous pressure to log in temperate rainforests. Thus, timber cutting is the number one threat to these forests. It should be noted that timbering can be very difficult here because of steep mountain slopes.

At the end of summer plant and animal life is at its fullest. Animals have matured and plants are fertile and in full bloom. In the fall things change. Animals breed and start getting ready for the winter and plants stop growing. The temperature also begins to drop during the fall as cool, crisp air replaces the hot, humid air.

Animals

Nocturnal animals, such as raccoons, flying squirrels, bats, and opossums, sleep in the trees during the day and have a full and active life at night. They wake up to forage or hunt for food. Other animals, like deer and black bears, are drowsy during the hot summer days and become more active during the cool nights. It is easy for predators and prey to hide from each other under the darkness of night. Animals that live during the day have to be trickier to hide themselves. Some animals live in burrows, trees, or the forest floor. Living in burrows is a safe refuge for small animals that need to hide from bigger animals.

The obvious element of climate in the temperate rain forest is precipitation. At least 200 cm of it, perhaps up to 350 centimeters in warmer areas. The precipitation can fall in the form of rain or snow, with snow becoming more likely at higher elevations. The average annual temperature is above 0� C, largely influenced by the nearby ocean. The warmest of the temperate rainforests may have average annual temperatures around 20� C.

These layers are:

1.The Top Layer (called the emergent layer)

Huge trees rising high above the rest of the forest, therefore receiving the most sunlight.

2.The second layer (called the canopy)

Tall trees growing close together so that their tops are close, forming a fairly continuous cover.

3.The third layer (called the understorey)

Smaller trees, bushes, and plants such as ferns, form the understorey. Not much sunlight reaches here, because the canopy blocks the sun.

4. The fourth layer (called the forest floor)

Few plants grow on the forest floor because almost no sunlight reaches it. The leaves and plants that drop from the upper layers provide food and shelter for animals and insects that inhabit the forest floor.